Sleep is a very important part of human's daily life, and sleep quality has a great impact on various aspects of one's metal and physical status, such as one's fatigue, mood, attention, and concentration, etc. High quality sleep can make a big difference in one's quality of life. Therefore, various instruments for evaluating sleep quality are emerging.
People often experience two different phases of sleeps during the night: Rapid Eye Movement (REM) sleep and non-REM sleep, which may alternately appear through the night. The periodical rhythm of the REM and the non-REM sleeps are called a sleep cycle. Non-REM sleep can be subdivided into 4 sub-stages, in which each successive stage of non-REM sleep is indicative of a deeper sleep, with stage 1 as the lightest and stage 4 as the deepest. FIG. 1 illustrates a typical person's sleeping stages through the night.
Polysomnography, which allows an evaluation of the sleep stages (Wake, REM, Non-REM) for identifying various forms of sleep disorders, remains a gold standard for sleep quality evaluation. However, polysomnography may have various limitations, such as cost, expertise required for measurement, and physical and psychological stress imposed on the examinee, which may narrow its applications to short term measurements on a small selection of patients. It may be unrealistic to use polysomnography for tracking long-term trends or for executing screenings on a large population, both of which are crucial for a further understanding of sleep.
Actigraphy has been proposed as a simpler alternative for quantifying sleep. To measure body movements through the night, actigraphy usually requires the examinee to wear a wristband shaped accelerometer. Actigraphy is easily administrable and non-invasive to the examinee, and the cost is low, which is favorable for a long-term use. However, Actigraphy may be unable to wake up a user pleasantly at a moment having a greatest satisfaction.
The disclosed systems and methods are directed to solve one or more problems set forth above and other problems.